In order for the extrusion process to be performed effectively, extruded materials often need to include a not inconsiderable water content, so that, after emerging from the extruder, they in many cases first have to be dried before being packed or used in some other way. Especially if the material is a food product, the drying process must as far as possible be performed in such a way that any contact between the material to be dried and germs or other micro-organisms can be ruled out. With conventional drying methods, in which there is contact between the material and dry air, it is, however, difficult to achieve general sterility.
The problem of the invention therefore consists in providing a method and an apparatus which make it possible to dry an extruded material efficiently without this entailing any contamination with undesirable germs.